MVA is a highly attenuated vaccinia virus deletion mutant, derived from the wild type virus by multiple serial passage in chicken embryo fibroblast cells. We employed the recently developed, highly efficient MVA expression vector to construct recombinants that contained the 80% E coding sequence of DEN4 or DEN2. Recombinant MVA-DEN2 80% E was shown to induce a higher level of neutralizing antibody response in mice than recombinant MVA-DEN4 80% E.Recombinant MVA-DEN2 80% E was evaluated in monkeys for immunogenicity and protective efficacy against DEN2 challenge. Monkeys inoculated with MVA-DEN2 80% E in a two-dose schedule developed a low to moderate level of DEN2 neutralizing antibodies. Partial protection against DEN2 challenge was achieved in monkeys immunized with the MVA-DEN2 80% E recombinant. Monkeys were then inoculated with MVA-DEN2 80% E in a three-dose schedule to determine if a booster response in antibody could be achieved and if solid protection against challenge would result. Three of the four monkeys tested developed antibodies against DEN2 at a titer significantly higher than that detected after the second inoculation and all four monkeys were completely protected against DEN2 challenge. The results showed that monkeys responded to a triple immunization schedule with the non-replicating MVA by becoming completely resistant to homotypic dengue virus challenge. The observed safety and efficacy of the candidate vaccine are encouraging and further studies to produce MVA-recombinants expressing highly immunogenic E of the other three dengue serotypes appear to be warranted. - Modified vaccinia Ankara (MVA), dengue envelope protein (E), recombinant, protective immunity, monkey model